SUMMARY/ABSTRACT Obesity and other weight-related problems, including poor dietary intake, inadequate physical activity, body dissatisfaction, and disordered eating behaviors, are of major public health concern, given their high prevalence and serious health consequences. The high prevalence of these problems in young people from low-income and ethnic/racial minority groups is of particular concern. This program of research aims to identify multi-level factors influencing a broad range of weight-related problems throughout key stages of the life course to guide the development of highly innovative, culturally acceptable, and effective interventions for populations in greatest need. The focus will be on the transition from adolescence to adulthood, an understudied, but important, period of life for the development of weight problems. This program of research is aimed at achieving the Principal Investigator's vision whereby young people from all backgrounds will have positive weight-related health, with support from their family, friends, schools, worksites, and neighborhoods. This Outstanding Investigator Award (R35-OIA) will support a highly productive and effective researcher and her team in a manner that will promote creativity, allow strategic risk-taking, and have a great impact on weight-related problems. The program of research combines a longstanding and well-defined cohort study with a flexible plan to address emerging topics of interest. The research program builds and expands upon the Project EAT (Eating and Activity in Teens and Young Adults) studies, the largest and most comprehensive longitudinal body of research examining multi-level predictors of a broad range of weight-related problems in young people. The research program will include the following: 1) 12-year longitudinal, multi-level follow-up data collection on weight-related problems from a diverse sample of young people (N=2,793) and their family, friend, school, worksite, and neighborhood environments; 2) intermediate and rapid response survey mechanisms to capture short-term changes and assess the impact of societal changes and emerging policies of potential relevance to weight-related outcomes; 3) innovative substudies using multiple methods for in-depth explorations of multi-level etiological processes to guide intervention development; and 4) a mentored training program for new investigators who will shape the future of the field of young adult weight-related health. This OIA comprehensive program of research will lead to the development of multi-level explanatory models for weight-related problems in young people and interventions for populations at greatest risk. Integration of a strong training program will ensure that the next generation of public health professionals has the tools to prevent marginalized populations from continuing to carry the burden of weight-related problems. Thus, this program of research builds on the NHLBI Strategic Vision, particularly regarding the objectives: 1) to investigate factors that account for differences in health among populations; and 2) to develop, diversify, and sustain a scientific workforce capable of accomplishing NHLBI's mission.